The invention relates generally to analytical systems. More particularly, the invention relates to a collection probe for use in a Raman spectrometer system.
The need for portable, rugged, high performance and low power analytical instruments is growing for a variety of defense and security applications where the ability to identify unknown substances is key. These expanding military needs require new instruments capable of detecting and resolving a large number of signatures from chemicals, biological analytes and mixtures thereof. These materials are potentially fluorescent as well as molecularly and structurally similar making identification very challenging. Given the danger posed by the presence of such biological and chemical agents in our immediate environment, whether in closed or open spaces, civilian areas or battlefields, it is imperative for such instruments to offer standoff and rapid detection capabilities as well as ruggedness to environmental conditions. This implies that minimal sample preparation is desirable and the analytical technique needs to be impervious to the presence of high percentage of water, immune to shock and vibrations and to numerous other environmental factors. Some of these desirable attributes are addressed by using Raman spectrometry. However, many of these capabilities, such as ruggedness and size still need to be addressed to make such a system portable and easier to be carried to inspection sites, rather than having to carry the sample back to the labs to be detected by these devices.
Photonic crystal based devices are employed for manipulating light in various ways. Typically, photonic crystal based optical devices with various functions including mirroring, waveguiding, splitting, collimation and spectral divergence are employed in analytical systems. While the implementation of these individual devices in a wide range of applications is very encouraging in demonstrating the capabilities of photonic crystals. Integrating the photonic crystal with other structures to form a practical optical system faces additional challenges. The integration of multiple optical components in these analytical systems employing photonic crystals require low loss optical couplers to transition the light between optical elements while maintaining polarization, mode profile with minimal scattering losses. Additionally, the fabrication processes needed to deposit, pattern, and etch these devices need to be highly integrated to enable multiple device and structure formation with the precision and accuracy necessary for device performance.
There exists a need for a collection probe for use in a portable analytical Raman system, which is integrated, compact and rugged.